Vapor phase corrosion inhibitor-dessiccant material

#The present invention relates to a formulation which is particularly adapted for use as a vapor phase corrosion inhibitor-desiccant, the material being useful for either inhibiting the corrosion of the metallic items and/or passivating the surfaces thereof, the formulation being particularly adapted for direct incorporation within synthetic resinous films through extrusion or deposition into a film, such as into an olefinic film, polyethylene, or the like. Film products prepared in accordance with the present invention find particular application in the formation of enclosures about metallic articles susceptible to corrosion, and provide a relatively dry corrosion inhibiting atmosphere therewithin. Specifically, the compositions of the present invention comprise a vapor phase corrosion inhibitor-desiccant wherein the vapor phase corrosion inhibitor component is selected from the group consisting of anhydrous sodium molybdate and mixtures of such molybdates with sodium nitrite and benzotriazole, and mixtures of benzoates of amine salts with benzotriazole and nitrates of amine salts. The desiccant component of the composition is a solid-phase granular particle consisting essentially of silica gel onto which the vapor phase corrosion inhibitor component, in powdered form, has been deposited thereon. These compositions provide a vapor phase corrosion inhibitor-desiccant which may be extruded along with a film material and with the film thereafter being utilized to form an enclosure housing the item or items being protected. Alternatively, the materials may be placed within enclosures or packages containing items which are to be protected from corrosion. For most-purposes, anhydrous powdered or finely divided mixtures of certain molybdates including anhydrous sodium molybdate, ammonium dimolybdate and amine molybdates along with mixtures of such molybdates with sodium nitrite and benzotriazole and mixtures of amine benzoates with amine nitrates and benzotriazole are preferred. These materials are then deposited upon the larger silica gel granules, with such vapor phase corrosion inhibitor components being preferred for such deposition applications. This composite mixture is preferably extruded into polyethylene film at a rate of from between about 2 percent and 3 percent by weight. Preferably, the silica gel particulate material has an average particle size ranging from between about 2 .mu.m and 8 .mu.m, with the vapor phase corrosion inhibitor component deposited on the surface of the granules having a size ranging from between about 0.001 micron and 0.1 micron.

#As an added feature of the invention, film materials extruded, with the formulations of the present invention may, in turn, be laminated to a second metallized film, such as, for example, metallized polyethylene terephthalate. The combined laminate provides a means to reduce and/or eliminate static build-up in or along the film, and accordingly improves the properties of the film when employed as an enclosure.

#In commerce and industry today, the useful life of corrodible items may be extended and/or preserved by providing corrosion inhibitors which protect the corrodible item from the adverse effects of its ambient environment. Corrosion inhibitors, particularly vapor phase corrosion inhibitors, have been found useful in protecting certain corrodible items against reaction with elements or compounds which may be found within their environment, and thereby losing their effectiveness, reducing their useful life, or otherwise diminishing their value. Such protection is typically needed during times of packaging, handling, shipment, or during end use. Elements or compounds which are normally of primary concern are gases such as oxygen, water vapor, sulfides, carbon dioxide, and the like. The vapor phase corrosion inhibitor-desiccant formulations of the present invention find particular application in the preparation of packaging material, particularly through in-situ extrusion of the material with such films, with the films thereafter being utilized to form an envelope or other enclosure about the article being protected. These films may also be employed as a member of a multi-layer laminate including a metallized film having good tear resistant properties such as stress-oriented polyethylene terephthalate containing a vapor deposited film or layer of metallic aluminum on a surface thereof. Such films are commercially available and are commonly designated as "aluminized" films.

#The FIGURE is a cross-sectional view of a typical laminate prepared in accordance with the present invention, with the center or metallized layer being shown in somewhat exaggerated form due to limitations of draftsmanship.

#In accordance with the preferred embodiment of the present invention, a particularly useful vapor phase corrosion inhibitor component for the composite material to be incorporated with extruded polyethylene film includes a mixture of either anhydrous sodium molybdate, anhydrous ammonium dimolybdate, or amine molybdates, together with sodium nitrite and benzotriazole. Specifically, in a particularly preferred embodiment, a mixture is provided in the following formulation:

#______________________________________ Component Percent by Weight ______________________________________ Anhydrous sodium molybdate 70% Sodium nitrite 25% Benzotriazole 5% ______________________________________

#This mixture is particularly effective when prepared in powdered form having a particle size below about 1 micron, and deposited upon granular silica gel. The relative weight ratios are preferably from between about 45% vapor phase corrosion inhibitor component, balance silica gel, although ratios of from between about 30% and 50% vapor phase corrosion inhibitor component, balance silica gel may be employed. The composite material is extruded into polyethylene film at a rate of 2% by weight. Effective mixtures have been found when extruded into polyethylene film at a rate of up to 3% by weight.